AB1324 DIFFERENCES IN PERIPHERAL BLOOD B-CELL SUBSETS IN PATIENTS WITH IGG4-RELATED DISEASE, PRIMARY SJOGREN’S SYNDROME AND HEALTHY DONORS
Authors: E. Sokol, A. Torgashina, B. Chalcev, J. Khvan, D. Tabakov, A. Aleksankin, M. Kireeva
Journal: Annals of the Rheumatic Diseases (2022)

Background The level of circulating plasmablasts has been proposed as a good marker for diagnosing and monitoring IgG4-related disease (IgG4-RD) independent of serum IgG4 level [1]. However elevated plasmablasts can be seen in other rheumatologic conditions. Objectives To compare В-cell subsets in peripheral blood of IgG4-RD, Sjogren’s syndrome (SjS) patients (pts) and healthy controls. Methods Twelve pts with clinically active IgG4-RD (7F/5M, mean age 50,25 years (range 33-62), 20 active SjS pts (19F/1M, mean age 42 years (range 32-54 years); median disease duration 3 (2-10) years; ESSDAI score ≥5 in 6 pts,) and 20 healthy donors were included. SS was diagnosed based on the ACR-EULAR 2016 criteria. IgG4-RD was diagnosed according to comprehensive diagnostic criteria (H. Umehara, 2011). CD19+ B cells, memory B-cells (CD19+CD27+), non-switched memory B-cells (CD19+IgD+CD27+), switched memory B-cells (CD19+IgD-CD27+), naïve (CD19+IgD+CD27-), double negative (CD19+IgD-CD27-), transitional (CD19+IgD+CD10+CD38+) B-cells, plasmablasts (CD19+СD38+++IgD-CD27+), and plasma cells (CD19+СD38+) were analyzed by multicolor flow cytometry using cytometer Navios (Beckman Coulter, USA). The nonparametric Mann-Whitney test was used for statistical analysis. Data were shown as median (Me) with an interquartile range of 25 - 75 percentile. The differences were considered statistically significant when p &lt;0.05. Statistica 10 for Windows (StatSoft Inc., USA) package was used for statistical data processing. Results There were no significant differences in the number of all studied B-cell subsets between pts with IgG4-RD and with SjS. But absolute numbers of plasmablasts, memory B-cells cells and transitional B-cells in IgG4-RD were significantly higher than in healthy donors: 4.5[1;9.8] х10 3 /μl vs. 0.2 [0.09;0.4] х10 3 /μl; 41 [33.5;57.5] х10 3 /μl vs. 2.5 [1;6.3]; 12 [6.5;21] х10 3 /μl vs. 0.1 [0;0.23] х10 3 /μl respectively, p&lt;0.05 for all cases. Table 1. Peripheral blood B-cell subsets in patients with SS and healthy donors. B-cell subsets, IgG4-RD SjS HD P&lt;0.05 Abs. х10 3 /μl B lymphocyte 166 [109.3;251.3] 164.5 [109.3;236.3] 150 [95;200] plasmablasts 4.5 [1;9.8] 2 [1;3.5] 0.2 [0.09;0.4] * transitional B-cells 12 [6.5;21] 8.5 [4;32.5] 0.1 [0;0.23] * switched cells 24.5 [20;41.8] 18.5 [11;29.8] 20 [9.75;40] non-switched cells 16.5 [10.5;21] 7 [3.75;15.5] 10 [4.75;20] memory B-cells 41 [33.5;57.5] 26 [14.8;40.8] 2.5 [1;6.3] * naïve B-cells 122 [63.3;176.5] 107.5 [49.5;193.8] 100 [57.5;100] double negative 13.5 [8.8;17] 10.5 [5.3;22.3] 20 [9.75;22.5] HD healthy donors * IgG4-RD and HD groups compared, р&lt;0.05 Conclusion Immunophenotyping showed disturbed homeostasis of the B-cells subpopulations in IgG4-RD pts with a significant increase in plasmablasts compared to HD, but there were no differences between IgG4-RD and SjS pts. Further research is needed to evaluate the diagnostic utility of circulating plasmablasts in IgG4-RD. References [1]Wallace ZS, Mattoo H, Carruthers M, Mahajan VS, Della Torre E, Lee H, Kulikova M, Deshpande V, Pillai S, Stone JH. Plasmablasts as a biomarker for IgG4-related disease, independent of serum IgG4 concentrations. Ann Rheum Dis 2015 Jan;74(1):190-5. Disclosure of Interests None declared